Coated golf ball

Abstract: The present invention provides a coated golf ball wherein whitening of color tone is enhanced and weathering properties are improved. The golf ball body having a cover mainly composed of an ionomer resin of the coated golf ball is coated with a white paint. A paint layer of the coated golf ball comprising at least one white paint layer and at least one clear paint layer. The white paint comprises 3 to 15% by weight of a white pigment, 0.0005 to 0.0250% by weight of a blue pigment and 0.001 to 0.010% by weight of a red pigment, based on 100% by weight of a solid content of a coat. The weight ratio of the blue pigment to the red pigment is 0.1 to 2.0.

Description: The present invention relates to a coated golf ball in which the golf ball body is coated with a paint. More particularly, it relates to a coated golf ball wherein a whitening of the color tone of the golf ball is enhanced and weathering properties are improved. A golf ball is roughly classified into three types, i.e. a golf ball having a balata cover, a golf ball coated with a cover mainly composed of an ionomer resin and an integrally molded type one-piece golf ball. All three golf balls are normally treated so that a white appearance is imparted thereto. Golf balls having balata covers are coated with a paint containing a large amount of a white pigment so as to cover the slightly subdued color of the balata cover itself. For golf balls coated with a cover mainly composed of an ionomer resin, the ionomer resin itself is transparent and the white pigment may therefore be contained in the ionomer resin. Therefore, the white appearance can sometimes be obtained by providing only a clear layer, without using a white paint. Even for golf balls having an ionomer resin cover, the adhesion after weathering is inferior when only a clear layer is provided. Furthermore, since the color tone depends upon the cover layer, a sufficient whiteness cannot be obtained. Particularly, the golf ball cannot be seen easily on green grass and, therefore, it is difficult to putt. In order to improve whiteness of the golf ball to enhance the commercial value thereof, U.S. Patent No. 5,029,870 suggests incorporating suitable amounts of blue and violet pigments into a white paint. However, the appearance of the resulting coated golf ball becomes dark white and, therefore, the golf ball cannot be seen easily when it is putted. We have now developed a coated golf ball wherein the whitening of color tone is enhanced and the weathering properties are improved. Accordingly, the present invention provides a coated golf ball in which a golf ball body having a cover mainly composed of an ionomer resin is coated with a white paint, the paint layer of the golf ball comprising at least one white paint layer and at least one clear paint layer, the white paint comprising from 3 to 15% by weight of a white pigment, from 0.0005 to 0.0250% by weight of a blue pigment and from 0.001 to 0.010% by weight of a red pigment based on the solids content of the coating, the weight ratio of the blue pigment to the red pigment being in the range of from 0.1 to 2.0. The white paint used in the present invention may be an epoxy, acrylic or urethane paint. A urethane paint is particularly preferred. For example, a white paint prepared by reacting an active hydrogen-containing compound (e.g. a polyester polyol or a polyether polyol) as a main material with an isocyanate compound as a curing agent is preferred. As the isocyanate compound, a 1,6-hexamethylene diisocyanate modified material (e.g. biulet material, trimethylolpropane modification, trimer, etc.) is preferred. A tolylene diisocyanate modified material is also preferred. The white paint contains a white pigment in an amount of 3 to 15% by weight based on the solids content of the coating. The white pigments may be those which have hitherto been used for the golf ball, for example titanium oxide or barium sulfate. When the amount of the white pigment is below 3% by weight, the weathering resistance becomes inferior. On the other hand, when the amount exceeds 15% by weight, the transparency and weight appearance become poor, and it is not preferred in view of the appearance. The amount is preferably from 5 to 12% by weight. In addition to the above components, various additives, curing catalysts and diluents are formulated in the white paint. Examples of the additive include ultraviolet inhibitors, fluid agents, sealing pigments, fluorescent agent and fluorescent brighteners. The amount of these additives is 0.1 to 10% by weight based on the solid content of the coating. As the fluorescent agent or fluorescent brightener contained in the white paint, for example, there are those which are normally known and are used for the golf ball. Examples thereof include 2,5-bis[5'-t-butylbenzoxazolyl (2) thiophene (commercially available from Japan Ciba Geigy Co. as Yubitex OB), 7-(2h-naphthol(1,2-d)-triazol-2-Y1)-3-phenyl-cusline (commercially available from Sanzos Co. as Leucopure EGM), biazoline derivative (commercially available from obey Chemical Corporation as Phorwhite K-2002), oxazoles (commercially available from Sumitomo Chemical Co., Ltd. as Whitefullar HCS, PCS, B) and fluorescent brightener (commercially available from Hoechst Japan Co. as Hostalux KCB). The amount thereof is 0.005 to 1.0% by weight based on the solid content of the coating. Examples of the diluent formulated in the white paint include ketones such as acetone and methyl ethyl ketone, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate. The amount of the diluent is not specifically limited, but it is generally 30 to 80% by weight. As the blue pigment, for example, phthalocyanine blue, indanthron blue, ultramarine blue, fast sky blue, cobalt blue or fanatone blue 6G, or a mixture thereof can be suitably used. The amount of the blue pigment is 0.0005 to 0.025% by weight based on the solid content of the coating. When the amount is not within the above range, sufficient whiteness cannot be obtained. The amount is preferably 0.0008 to 0.020% by weight. As the red pigment, for example, quinacridone magenta or permanent red fast scarlet VD, or a mixture thereof can be suitably used. The amount of the red pigment is 0.001 to 0.010% by weight based on the solid content of the coat. When the amount is not within the above range, sufficient whiteness can not be obtained. The amount is preferably 0.0012 to 0.008% by weight. By coating the above paint on the golf ball body, a coated golf ball of which color tone shows an L value of 85 to 95, an a value of 0 to 2.0, a b value of -6.5 to -10.0, a Wcie value of 108 to 125, a Tw value of 2 to 5 and a Wcie/Tw value of 22 to 50, can be obtained. When these values are not within the above range, the resulting coated golf ball lacks in whiteness. Preferably, it shows an a value of 0.05 to 1.5 and a b value of -7.0 to -9.5. These values are measured by a colorimeter available from Minolta Co., Osaka, Japan. The golf ball body has a cover mainly composed of an ionomer resin. The resin for the cover may contain various pigments. It is preferred that 1 to 6 parts by weight of the white pigment and 0.002 to 0.08 parts by weight of the blue pigment are formulated in 100 parts by weight of the resin for the cover. As the white pigment, there can be preferably used titanium oxide or barium sulfate, or a mixture thereof. As the blue pigment, there can be used various pigments which have hitherto been known. The coated golf ball of the present invention can be produced by applying the clear paint after the white paint is applied on the golf ball body, plural times. The clear paint is one which essentially contains no pigment, and there can be used an epoxy, acrylic or urethane paint. The clear paint is known as to the production of the golf ball. According to the present invention, a coated golf ball wherein whitening of color tone is enhanced and weathering properties are improved can be obtained. EXAMPLES The following Examples and Comparative Examples further illustrate the present invention in detail. Examples 1 to 5 and Comparative Examples 1 to 3 Paints A to E (Examples) and paints F to H (Comparative Examples) were prepared by mixing the components shown in Table 1 according to a conventional method. On the golf ball body with a cover made from a resin prepared by formulating 4 parts by weight of a white pigment (e.g. titanium oxide or barium sulfate) and 0.02 parts by weight of a blue pigment (e.g. ultramarine blue) in 100 parts by weight of a resin mainly composed of an ionomer resin, a white coat of two layers was formed using the above paint. Thereafter, the color tone, the feature of appearance, the color tone due to visual observation and the bond strength after weathering test were evaluated. The kind of the paint used and test results are shown in Table 2, below. Test method (1) Measurement of color tone Colorimeter CR221 manufactured by Minolta Co. (visual field of 2°, 3 mm, light source D 65 ), according to Y x y measurementThe formula of whiteness degree of CIE•ISO: Wcie = Y + 800 (X 0 - X) + 1700 (Y 0 - Y) Tw = 1000 (X 0 - X) - 650 (Y 0 - Y) wherein X 0 and Y 0 are respectively chromaticity coordinate of perfect diffuser of D 65 lighting, X 0 is 0.3127 and Y 0 is 0.3291. (2) Visual observation (feature of appearance) Whiteness was evaluated by 200 random panelists according to the following criteria: 4: considerably white 3: white 2: white but contains some other color 1: yellowish white (3) Measurement of bond strength after weathering test A coated golf ball was struck against a iron plate at a speed of 45 m/second, 50 times after treating with a sunshine weatherometer for 120 hours. Thereafter, a bond strength of a paint layer was measured. o ○: No peeling ×: Severe peeling

Claims: A coated golf ball in which a golf ball body having a cover mainly composed of an ionomer resin is coated with a white paint, the paint layer of the golf ball comprising at least one white paint layer and at least one clear paint layer, the white paint comprising from 3 to 15% by weight of a white pigment, from 0.0005 to 0.0250% by weight of a blue pigment and from 0.001 to 0.010% by weight of a red pigment based on the solids content of the coating, the weight ratio of the blue pigment to the red pigment being in the range of from 0.1 to 2.0. A coated golf ball as claimed in claim 1, wherein the color tone of the coated golf ball has an L value of 85 to 95, an a value of 0 to 2.0, a b value of -6.5 to -10.0 and Wcie representing whiteness of 108 to 125. A coated golf ball as claimed in claim 2 wherein the color tone has an a value of 0.05 to 1.5. A coated golf ball as claimed in claim 2 wherein the color tone has a b value of -7.0 to -9.5. A coated golf ball as claimed in any one of the preceding claims which comprises from 0.0008 to 0.020% by weight of the blue pigment. A coated golf ball as claimed in any one of the preceding claims which comprises from 0.0012 to 0.008% by weight of the red pigment.

Inventors: HORIUCHI KUNIYASU, MARUOKA KIYOTO, HORIUCHI, KUNIYASU, MARUOKA, KIYOTO
Applicants: SUMITOMO RUBBER IND, SUMITOMO RUBBER INDUSTRIES, LTD.
Application year: 1994
Main classification: C09D7
IPC codes: C09D7, A63B37